Co-encapsulation of gallium with gentamicin in liposomes enhances antimicrobial activity of gentamicin against Pseudomonas aeruginosa.
OBJECTIVE
The aim of this study was to enhance the antimicrobial efficacy of a liposomal gentamicin formulation with gallium metal (Lipo-Ga-GEN) against clinical isolates of Pseudomonas aeruginosa.


METHODS
Sputum isolates of P. aeruginosa from cystic fibrosis patients were used to determine the MIC and MBC of Lipo-Ga-GEN. P. aeruginosa biofilms were formed and used to compare the minimum biofilm eradication concentration of the conventional drugs with that of Lipo-Ga-GEN. Quorum sensing (QS) molecule reduction of P. aeruginosa was determined by monitoring N-acyl homoserine lactone production using Agrobacterium tumefaciens reporter strain (A136). Viability of the cultured human lung epithelial cells (A549) was determined by Trypan Blue assay in order to assess Ga toxicity.


RESULTS
MIC and MBC values indicated that gentamicin was more effective against a highly resistant strain of P. aeruginosa (PA-48913) when delivered as a Lipo-Ga-GEN formulation (256 mg/L free gentamicin versus 2 mg/L Lipo-Ga-GEN). Lipo-Ga-GEN was the only formulation that completely eradicated biofilms and blocked QS molecules at a very low concentration (0.94 mg/L gentamicin). The decrease in cell viability was less in A549 cells exposed to Lipo-Ga, suggesting that encapsulated Ga is safer.


CONCLUSIONS
The results clearly indicate that the Lipo-Ga-GEN formulation is more effective than gentamicin alone in eradicating antibiotic-resistant P. aeruginosa isolates growing in a planktonic or biofilm community.
Halwani
M
M
The Novel Drug and Vaccine Delivery Systems Facility, Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada P3E 2C6.
Yebio
B
B
Suntres
Z E
ZE
Alipour
M
M
Azghani
A O
AO
Omri
A
A
D054742:Acyl-Butyrolactones / Q000378:metabolism; D016960:Agrobacterium tumefaciens / Q000254:growth & development; D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival; D003550:Cystic Fibrosis / Q000150:complications; D004357:Drug Synergism; D004847:Epithelial Cells / Q000382:microbiology; D005708:Gallium / Q000378:metabolism* / Q000494:pharmacology*; D005839:Gentamicins / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D008081:Liposomes / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D013183:Sputum / Q000382:microbiology; D014343:Trypan Blue / Q000378:metabolism
D054742:Acyl-Butyrolactones; D000900:Anti-Bacterial Agents; D005839:Gentamicins; D008081:Liposomes; D005708:Gallium; D014343:Trypan Blue